These mats have applications in fuel and solar cells, smart textiles, and in wound dressings and tissue engineering scaffolds.
A modified electrospinning apparatus has been created for spinning highly aligned polymer fibers. Fiber placement, orientation, and porosity are difficult to control using conventional electrospinning apparatus. Conventional electrospinning creates randomly oriented fibers that are well suited to nonwoven mats, but not to other applications. This new technology will broaden the range of engineering applications of electrospun materials. The apparatus provides a simple and inexpensive means of producing fibers and mats of controlled fiber diameter, porosity, and thickness.
Benefits include the following:
- Consistency and control of fiber distribution, porosity, and fiber alignment,
- Adaptability to micro and nano fiber sizes,
- Repeatable results that are amenable to mass production,
- Capability of manufacturing single fibers,
- Compatibility with most polymer solution systems, and
- Inexpensive processing method.
The apparatus uses an auxiliary counter electrode to align fibers for control of the fiber distribution during the spinning process. The electrostatic force imposed by the auxiliary electrode creates a converged electric field, which affords control over the distribution of the fibers on the rotating collector surface. The process begins when a pump slowly expels polymer solution through the tip of the spinneret at a set flow rate as a positive charge is applied. The auxiliary electrode, which is negatively charged, is positioned opposite the charged spinneret. The disparity in charges creates an electric field that effectively controls the behavior of the polymer jet as it is expelled from the spinneret. It ultimately controls the distribution of the fibers and mats formed from the polymer solution as it lands on the rotating collection mandrel. A broad range of fiber diameters can be manufactured by modifying various parameters of the process and/or polymer solution.
The technology offers wide-ranging market applications, including tissue engineering scaffolds for cell formation, drug delivery, and wound dressing; military smart textiles and embedded sensors/actuators; industrial, environmental, and automotive filters; sensors for spectroscopy; chemical and biological sensors; and fuel cells and solar cells.
This work was done by Ralph M. Stephens, Nancy M. Holloway, and Emilie J. Siochi of Langley Research Center; and Lisa A. Scott-Carnell, Caroline Rhim, Laura E. Niklason, and Robert L. Clark of Duke University. For further information, contact the Langley Technology Transfer Office at (757) 864-8881. LAR-17477-1.